The present invention relates to a plant for distilling air and for generating electricity, of the type comprising, on the one hand, an air distillation apparatus having at least one outlet for a nitrogen-rich fluid and an outlet for a product to be delivered in the liquid state and, on the other hand, a gas turbine unit comprising a combustion chamber and an electricity-generating turbine, the intake of which is connected to an outlet of the combustion chamber, the plant furthermore comprising means for expanding a nitrogen-rich fluid in order to generate refrigerating power allowing the said liquid product to be delivered, the air distillation apparatus being connected in parallel to these expansion means and to the intake of the electricity-delivering turbine in order to feed them with at least one nitrogen-rich fluid.
It is frequent on industrial sites for a gas turbine unit to be alongside an air distillation apparatus. The gas turbine unit and the air distillation apparatus generally operate independently.
The gas turbine unit contributes, for example, to the supply of an electrical distribution network.
The air distillation apparatus delivers products coming from the air distillation, typically a nitrogen-rich fluid and an oxygen-rich fluid. At least one of these products is usually delivered in the liquid state, making it easier to store it.
The maximum instantaneous electrical power that a gas turbine unit can deliver is generally limited by the characteristics of the compressor that such a unit usually has upstream of its combustion chamber.
A plant of the aforementioned type is also known from EP-A-0 465 193. In this plant, the stream of nitrogen-rich fluid sent to the electricity-generating turbine is used to increase the maximum power delivered by the gas turbine unit above the limit imposed by the characteristics of the compressor of this unit. Thus, it is possible, by virtue of this characteristic, to modify a plant for distilling air and for generating electricity in order to meet a permanent increase in the requirements of consumers of the electrical distribution network.
However, the plant described in that document does not allow it to be adapted to the seasonal variations in the requirements of the consumers of such a network.
It is one of the objects of the invention to solve this problem by providing a plant of the aforementioned type allowing it to be easily adapted to the temporary variations in the electricity requirements of the consumers of a distribution network supplied by this plant.
For this purpose, the subject of the invention is a plant of the aforementioned type, characterized in that it comprises control means for controlling the flow rates of the nitrogen-rich fluid streams sent to the expansion means and to the electricity-generating turbine, respectively, and determination means for determining the electrical power to be generated by the electricity-generating turbine.
Depending on the particular embodiments, the plant may comprise one or more of the following characteristics, taken separately or in any technically possible combinations:
the expansion means comprise a turbine;
the plant includes a heat exchanger for cooling the liquid product to be delivered, connected to the outlet of the expansion means;
the plant includes a heat exchanger for cooling the air to be distilled, connected to an outlet of the expansion means;
the plant includes means for compressing a nitrogen-rich fluid, these being placed between the air distillation apparatus and the intake of the electricity-generating turbine;
the plant includes means for warming a nitrogen-rich fluid, these being placed between the air distillation apparatus and the intake of the electricity-generating turbine;
the air distillation apparatus is connected in parallel to the expansion means and to the electricity-generating turbine via the same nitrogen-rich fluid outlet;
the plant includes a control unit for controlling the flow rate means, which unit is designed to increase the flow rate of the nitrogen-rich fluid stream feeding the electricity-generating turbine when the electrical power to be generated increases; and
the control unit is designed to decrease the flow rate of the nitrogen-rich fluid stream feeding the electricity-generating turbine when the electrical power to be generated decreases.
The subject of the invention is also a process for generating electricity and for distilling air by means of a plant as defined above, characterized in that the flow rate of the nitrogen-rich fluid stream feeding the electricity-generating turbine is increased when the electrical power to be generated increase.
According to a variant, the flow rate of the nitrogen-rich fluid stream feeding the electricity-generating turbine is decreased when the electrical power to be generated decreases.